Collimator



FIG. 1 is a back and side perspective view of a collimator embodying ournew design;

FIG. 2 is a front and side perspective view thereof;

FIG. 3 is front view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a bottom view thereof;

FIG. 7 is a right side view; and,

FIG. 8 is a back view thereof.

CLAIM The ornamental design for a collimator, as shown and described.